No. 91-442 IN THE SUPREME COURT OF THE STATE OF MONTANA 1992

IENRY E. NELSON, Claimant and Appellant,-vsSEMITOOL, INC., and EBI ORION GROUP, Defendants and Respondents.

APPEAL PROM: District Court of the Workersf Compensation Court, The Honorable Timothy W. Reardon,Judgepresiding.

COUNSEL OF RECORD: For Appellant: Kenneth E. O'Brien, Hash, O'Brien & Bartlett, Kalispell,Montana. For Respondent: Robert E. Sheridan, Garlington, Lohn 6 Robinson, Missoula, Montana.

Submitted on ~riefs: February 13, 1992
Filed:Justice R. C. McDonough delivered the Opinion of the Court.
Henry E. Nelson (Nelson)appeals from anorder of theWorkerse Compensation Court attributing fifty percent of his disability to

an occupational disease resulting from his employment with the respondent, Semitool Inc., and fifty percent to a preexisting disability. Nelson asserts that the occupational disease from which he suffers is fully compensable by Semitool and was inappropriatelyapportionedby the Department of Labor. We affirm. The single issue for our review is whether the Workerse Compensation Court erred by apportioning fiftypercent of Nelson's current disability to a preexisting disability. From 1964 until 1969, Nelson was an employee of the United States Postal Service. While employedby thepostal serviceNelson injured his back necessitating a lumbar spinal fusion. His back condition prevented him from performing his postal service duties and he began receiving federal workers' compensation benefits. Nelson received full disability benefits until 1978 and appears to continue to receive partial benefits at present. From 1978 until 1982, with the exception of approximately

seven months, Nelson worked as a hardware store clerk. There is conflicting evidence regarding what, if any,back problems Nelson experienced while employed as a clerk. There is evidence that Nelson consulted with a local orthopedist and reported low back pain that radiated into his legs during this period. 

### In 1982,Nelson began working for Semitool, Inc. Because ofhisprior back condition,Semitool requiredaphysical. Nelson was cleared to lift 100 pounds on a regular basis. From 1982 until 1988 Nelson held several jobs with Semitool, each of which

resented severe physical demands including heavy lifting. In 1988, Nelson began experiencing back problems which grew progressively worse culminating in Nelson's inability to continue work, The Department of Labor directed thatNelsonbe examined by a member of the Occupational Disease Panel to determine if he suffered from an occupationaldisease. Nelson was examined by Dr. W,J. McRinstry who concluded that Nelson's back problems were related to his employment at Semitool. A second examination was conductedby Dr. PlcDonaldwho concluded that Nelson'sbackpain was not attributable to his work at Semitool but to his prior injury and the lumbar fusion. Because of the differing opinions,a third doctor, Dr. Jacobson,was appointed to review the case and act as referee. Dr. Jacobson concurred with Dr. McDonald and on this basis the Department of Labor denied Nelson benefits under the Occupational Disease Act. Nelson appealed theDepartmentof Labor decision and ahearing examiner was appointed. The hearing examiner determined that Nelson did suffer from an occupational disease as a result of the work at Semitool but that under 539-72-706, MCA, Semitool was (only fiftypercent responsible for the current condition. Both parties to the Workers' Compensation Court and the hearingexaminer's conclusion was affirmed. In addition to the reports and depositions of the above mentioned examining doctors, the record includes the opinions of Nelson's treatingphysicians,Drs. Ingham and Stephens. All of the doctors appear to agree that Nelson is suffering from a condition called spinal stenosis. Spinal stenosis is the narrowing of the area through which the nerves pass in the spinal column. The stenosis in Nelson's case is a result of increased bony growth or hypertrophic bone growth that has developed at the site of the 1968 bone fusion. There is conflicting evidence regarding whether or nat the work at Semitool caused, accelerated, aggravated or is totally unrelated to Nelson's condition. Nelson argues that at the timehewent towork for Semitoolhe

was completely recovered fromhisprior injury and thathis current condition is the result of hiswork at Semitool. Therefore,Nelson contends Semitool is liable for onehundred percent of his current occupational disease. There is no dispute that Nelson is disabled at least part of the disability is an occupational disease resulting from his work for Semitool. The current dispute requiring our resolution is whether, under § 39-72-706, NCA, Nelson's disability is appropriate for apportionment between his preexisting condition and the occupational disease. Section 39-72-706,MCA, provides in pertinent part: 

### Aggravation. (1)Ifanoccupational disease isaggravated by any other disease or infirmitynot itself compensable or if disability ordeath fromany other causenot itself compensable is aggravated, prolonged, accelerated, or inany way contributed to by an occupational disease, the compensation payable under this chaptermust be reduced and limited to such proportion only of the compensation that would be payable if the occupational disease were the sole cause of the disability or death as such occupational disease as a causative factor bears to all the causes of such disability or death. The Workers"ompensation Court concluded that employment with Semitool accelerated Nelson's disease to the extent that Nelson could no longerperform his job. Semitool was held liable for the portion of the disability determined to be aggravated and accelerated by Nelson" employment with them. The remaining Xiability was affixed to Nelson's preexisting condition. It is not the function of this Court to reweigh the evidence. We will uphold the findings and conclusions of the Workers1 Compensation Court if they are supported by substantial credible evidence in the record. Eastman v. Atlantic Richfield Co. (19891, 237 Mont. 332, 777 P.2d 862. Where the findings are based on conflicting evidence,the Court's function is to determinewhether there is substantial evidence to support the findings and not to determine whether there is sufficient evidence to support contrary findings. Littlev. Structural Systems (19801, 188 Mont. 482, 614 P.2d 516. There isno dispute that Nelson suffers from spinal stenosis. Furthemore,thedoctorsagree thathad the original injury and the resulting fusionsurgery never occurred, it isunlikely thatNelson would have ever developed spinal stenosis. There is evidence, although the doctors dispute whether it is merely possible orwhether it is probable, that strenuous physical activity accelerates hypertrophic bone growth and the development of spinal stenosis. It was not possible for the physicians to determine if the stenosisdeveloped prior to or after Nelson began working for Semitool. However,there isevidence thatNelson continued tohave back problems in the years immediately preceding his work with Semitool. Nelson contends that becausehispreexisting conditiondid not prevent him from working at Semitool it is not a disability that permits apportionment. Furthermore, he contends that the occupational disease from which he suffers is spinal stenosis, a distinct and separate condition from the original postal service injury that required the fusion surgery. Nelson refers to Larsen's treatise on Workers' Compensation wherein Larsen states: To be apportionable,then, an impairment must have been independentlyproducing somedegree of disabilitybefore the accident, and must be continuing to operate as a source of disability after the accident, Larsen

### 's Workers' Compensation, Volume 2, Section 59.22(c), Page 10-401. We do not find the conclusion of theWorkers' Compensation Court to be inconsistent with Larsen as cited above. There is substantial evidence that the original back injury was an impairment that "independentlyproduced some degree of disability". For example, claimanthad to leave a previous job due to hisback injury. There is also substantial evidence to support the finding that theprior injury is the source of Nelson's current disability. Section 39-72-706, MCA, requires that if a disability fromanother cause is aggravated or accelerated or in any way contributed to by an occupational disease, compensation for the occupational disease is reduced in a proportional amount. We conclude that substantial evidence exists that cumulative trauma from work at Semitool aggravated Nelson's preexisting back disability. The Workers' Compensation Court is affirmed.

r7' i/ We Concur: ,,*March CERTIFICATE 1hereby certifythat the followingorder w; followingnamed:

Kenneth E.O'Brien Hash, O'Brien &Bartlett P.O.Box 1178 Kalispell, M'T 59903 I,1992 OFSERVICE gent by Unitcd States mail,prepaid, to the

Robert E. Sheridan Garlington, hhn&Robinson P.0. Box7909 Missoula, MT 59807 ED SMITH CLERK OFTHE SUPREME COIJRT STATE OFMONTANA